Hermetic refrigeration compressor



Feb. 26, 1952 A J. roUBoRG 2,587,246

HERMETIC REFRIGERATION COMPRESSOR Filed Nov. 28, 1949 3 Shees-Sheel lFQJ. 22 f ffg nl x x v Bnnentor B @aa/#1% ZW Citt meg Feb. 26, 1952 1TOUBQRG 2,587,246

HERMETIC RFRIGERATION COMPRESSOR Filed Nov. 28, 1949 3 Sheets-Sheet 2JQDS j'uborg Feb. 26, 1952 J. TOUBORG 2,587,246

HERMETIC REFRIGERATION COMPRESSOR Filed Nov. 28, 1949 3 Sheets-Sheet 5Jens Toubaf BB M W omeg Patented Feb. 26,

A 2,587,246 HERMETIC REFRIGERATION COMPRESSOR Jens Touborg, Tecumseh,Mich., assignor to Tresco, Inc., a corporation of Michigan ApplicationNovember 28, 1949, Serial No. 129,738

7 Claims. (Cl. 2304-58) This invention relates to compressors of thewhich is also described in my prior and copending application, SerialNo. 51,348, led September 27, 1948, and to that extent this applicationmay be deemed a continuation in part.

One of the problems presented in connection with small or fractionalhorsepower compressors, to be used in conventional refrigeratingsystems, is the elimination of noise. Another problem is to assureadequate supplies of lubricant to the working parts, such as the motorshaft. It has heretofore been proposed to include a small auxiliary pumpin the compressor assembly to deliver oil to the working parts, but ithas been found, under many conditions of operation, that a pump havingadequate capacity also generated a relatively loud noise, and thusdetracted from one of the desired attributes of the compressor. Anotherproblem encountered in the provision of a lubricant pump is that manyproposals require a substantial number of additional parts, complicatedporting and conduit arrangements and the like, and thus unduly increasethe cost.

According to the present invention, a lubricant pump of high capacity,and which has been found to be substantially noiseless in operation, isbuilt into the compressor assembly, and is so devised as to requiresubstantially no additional parts, and a minimum of machiningoperations. In a preferred embodiment of the invention, the pumpingeffect is obtained by inclining a reciprocating piston-in-cylindercompressor with respect to the axis of the drive shaft, and utilizingthe resulting relative linear motion between the crank pin and pistonyoke to force oil into a duct drilled in the drive shaft. Additionally,the crank pin is also inclined to the axis of the drive shaft, to impartan arcuate oscillatory motion to the piston about its longitudinal axis.as well as a linear reciprocating motion. The compounded motion of thepiston provides a wiping action within the cylinder, which laps orpolishes out score marks that might otherwise be formed by adventitiousdirt particles. Such motion moreover maintains the piston in motion inat least one direction at all times, and thus further eliminates orreduces a noise factor which is an incident to, or inherent in,reciprocating pistons whose linear motion is truly or approximatelyharmonic.

The principles of the invention, and the ad' vantages to be derivedtherefrom, will be made apparent from the following description of atypical embodiment, illustrated in the accompanying drawings, wherein:

Fig. 1 is a vertical section through a hermetic compressor incorporatingthe invention;

Fig. 2 is a bottom plan;

Figs. 3 to 6 inclusive are enlarged fragmentary -horizontal sectionsthrough the cylinder and piston assembly of the compressor, showing therelative positions of the parts at -ninety degree intervals during acomplete revolution of the drive shaft;

Figs. '7 and `a are enlarged fragmentary vertical sections through thecylinder and piston assembly, showing the positions corresponding tothose shown in Figs. 3 and 6, respectively;

Fig. 9 is an exploded view, partly in section and partly in elevation,of the drive shaft, crosshead. and piston and yoke of the compressor;

Fig. 10 is an additionally enlarged bottom plan of the crosshead; and,

Fig. l1 is a top plan of the piston and yoke assembly.

Referring primarily to Figs. 1 and 2, the compressor (in common withthat'disclosed in my above identified prior application) comprises atwo-part casing or shell including flanged sections 2| and 22, which arerelatively shallow with respect to their diameters, and which are weldedtogether after assembly to provide a hermetically sealed compressor.Within the casing are an electric motor 23, main casting 24, and arefrigerant pump or compressor 25, all of which. are connected togetherand are resiliently mounted in spaced relation to the casing walls. Thecasting 24 is generally annular in form', and it is provided atdiametrically opposed points with outstanding lugs 26, each of which istransversely bored to receive mounting means, as will presently bedescribed. The casting 24 is centrally formed with anupstandlng bearingboss 21, which is axially bored to receive a vertically disposed maindrive shaft 28, whose ends project both above and below the boss.

The upper end of the shaft 28 receives a bored and counterbored quill 3|provided with a sleeve 32 whose lower end is supported on the upper endof the boss 21 through the medium of a thrust washer 33. The sleeve issuitably connected to the upper end of the shaft 28, as. for example, bymeans of a press iit. A motor rotor 34 is also press fitted into the quill 3|. The motor stator 35 is mounted on a. shoulder 36 'through theaperture 45.

anemie formed onine periphery or the casting u. and ,it

is secured in position by any suitable means, such as bolts, not shown.The motor lead wires 31 extend to terminals 38 which pass through thewall of the casing section 22, and into a relay box,39, welded to thecasing, wherein the indicated electrical connections may be made.

The casting 24 and the parts connected thereto are internally mounted inthe casing by a resilient suspension cooperating with the casting lugs26. The casing sections are each provided with spaced padportionsM, 42,located substantially radially equidistant from the longitudinal axis ofthe cylindrical dimension of the casing, and in an axial plane parallelthereto. Opposed pads may therefore bebrought into alignment when thecasing sections are superimposed. As

described in detail in my aforesaid copending application, each pad isprovided 'with an abutment or socket 43 which is welded thereto, toreceive the ends of transversely extending spring supporting andretaining rods 44, which pass through tapped apertures 45 in the lugs26. Each rod is surrounded by a coiled spring 4 6 which also passes Thesprings 46 are both helical and cylindrical, and they are-screwed/intothe apertures 45 to project on each side thereof the proper distance tocenter or locate the compressor assembly within the casing. While thesprings contact the lugs, they do not contact the rods 44 except at theends thereof,.where they are bent into a generally hairpin convolutiontogrip the' rod on opposite sides, and around a small key 41 formed oneither end thereof. These keys prevent rota.- tion of the springs androds relative to each other after the assembly has been made andadjusted. -The casing section 22 is also provided with dependingbrackets 48, disposed above the lugs 26, to whichvare connected one yendof. tension springs 49, whose opposite ends engage openings formed inears 5I of the lugs 26. The springs 4S absorb some of the weight of theassembly, andin conjunction with the springs 46, permit the resilientmounting of the parts in such fashion that forced vibrations, andresulting noise, is

minimized. l

The refrigerant pump unit 25 comprises acylinder block having'acylinder, 56 bored therein, the head end of which is covered by a valveplate 51 and-cylinder head 58. Inasmuch as the details of the valvesform no part ofthe present invention, and suitable structure is morefully described in my prior application, a further description of theseparts appears unnecessary. The cylinder block 55 is secured to the underside of the casting 24 by bolts 59.- A piston 6I is reciprocably mountedin the cylinder 56 by means of an offset or crank portion 62 formed onthe lower end of the main shaft 28, and below aV crank' arm 63 whichcarries a counterweight 64. The crank 62 rotatably ts into a diametricalbore 65 of a cylindrical crosshead 66, which is Vcarried for ltransversereciprocatory movement in turning refrigerant vapors into the cylinder56 v 4 The returning vapors line 1I at the top of the casing, flowaround .the motor to absorb-some of its heat. and enter the cylinderhead 68 through a suction tube 12 which extendsupwardly in the casingand above the oil level therein. The discharged vapors pass through adischarge line 1I which yis advantageously coiled in the oil bath at thebottom of the casing, and which terminates in an outlet line 14 passingthrough the casing wall. The compressor is adapted to be included in theusual compressor condenser expander refrigeration system. which needs nodescription here.

Considering further'the cylinder and piston and 'drive assembly. it willbe seen, in Fig. 1 and' some -of the enlarged views, that the cylinderblock $5 and the cylinder bore 58, are inclined at a slight angle to thehorizontal plane. Similarly, while the motor and bearing portions of themain shaft 28 are disposed in a vertical plane, the crank portion 62 isinclined to the vertical plane. The piston 6I is, of course, alsonecessarily inclined to the horizontal plane, and it follows that it isnot at right angles to the vertical. These inclinations depart fromcustomary practice, and lead to the improvements with which the presentinvention is primarily concerned. It may here -be noted that while thisangularity may be varied within reasonably wide limits, the drawingshave here been laid out for deviations from the horizontal and verticalreference lines or planes for a fairly small angle, between two andthree degrees. This is sufllcient for a compressor subject to theintended service of the illustrated unit.

As will be readily understood by those conversant with the Scotch yokelinkage, rotatlon of the drive shaft 28 about its own axis causesanorbital movement of the 'crank pin 62, which, in the usualorconventional casedescribes or sweeps out a right cylinder whose axiscoincides with the axis of the drive shaft. The crank pin 62 rotatablyrits in the bore 65 of the crosshead 66,' and the crosshead is guided inthe bore of the transverse yoke 61. During one revolution of the driveshaft. the crosshead will therefore move lengthwise of the yoke with alinear reciprocatory motion, and the crosshead, yoke, and piston willalso have a linear reciprocatory motion with respect to the longitudinalaxis of the cylinder 56. The successive positions assumed by these partsare shown in Figs. 3 to A6, wherein Fig. 3 represents the end of thesuction stroke and the beginning of the compression stroke.Counterclockwise rotation as viewed in these figures, will be assumedthroughout the balance of the description. The piston 6| is thenbeginning to move to the left, and the crosshead 66 ismoving in anupward direction.

In the ensuing ninety degrees of rotation, the displacement of the crankpin 62 has moved the crosshead 66 upwardly to the limit of its travel Ain this direction, and has also moved the piston 6I about half way inits stroke into the cylinder 56. Thisis shown in Fig. 4. In Fig. 5, theend of the compression stroke has been reached, and the displacement ofthe crankpin has caused the crosshead to recede from the upper end ofitsl lenter through a suction the upper portion ofthe yoke, and thelength of the pin 62 is such as to terminate adjacent the innermostchord taken through the arcs of intersection of the bore 65 and theperiphery of the crosshead 66.

` As noted, the piston 6| and crank pin 62 are inclined to the normalaxes, and therefore the arcuate motion of the crank pin is not such asto describe a cylinder, but rather a cone or frustum of a cone. That isto say, the inclination of the crank pin 62 causes its lower extremityto sweep through a circle of larger diameter than that traced by itsupper end. As the crank pin 62 is fitted uniformly in the cylindricalbore 65 of the crosshead 66, it will be apparent that the crosshead willhave a rocking or pendulum like motion about the vertical axis as itmoves from-one end of the yoke to the other. Similarly, the inclinationand motion of the crank pin will cause the yoke 61, and the connectedpiston 6|, to have a rocking motion about the vertical axis. In Figs. 3to 6, wherein the vertical axis is normal to the plane of the paper, therocking motion of the piston 6| is the same as an arcuate oscillatorymotion of the piston about the axis of the cylinder 56, and it is hereinillustratedby black dots on the piston surface, which show thedisplace.- ment on either side of the center line. If thes'e successivedot positions were connected, they would outline a relatively long ovalor ellipse.

The effect of the combined linear and arcuate movements of the crossheadin the yoke, and the piston in the cylinder, is to change the alignment82, 83,formed in the casting 24 (see also Fig. 1).

'for delivery to the exposed portion of the piston 6|.' The excess Oilfalls by gravity to the oil bath contained in the bottom or crankcaseportion of the casing; j

Theiower and Vcrank pin portions of the shaft 28 are longitudinallydrilled to provide a duct between longitudinal lines of contact betweenthe pairs of arcuate surfaces, thus producinga wiping or lapping actionwhich otherwise would not be obtained. This motion is beneficial, as itserves to effect a better distribution of the oil films between thesurfaces, and it increases the resistance to the introduction of smalldirt particles which would cause scoring.

otherwise, the linear and arcuate motions are` out of phase, and, inthis particular case, by approximately 180. Inasmuch as the end of thedisplacement or stroke of a body having har monic motion is accompaniedby a reversal of direction of motion, the body, at the instant ofreversal, has a zero velocity, while maximum velocity occurs as itpasses through its centralpoint of reference. Thus, when the piston 6|reaches the end of its linear movement or stroke, its arcuate velocityis at its maximum, and thel piston is therefore always in motion. It hasheretofore been observed that the reversal of stroke of a conventionalpiston-in-cylinder compressor has been accompanied by a slight hiss ornoise, which was considered to be inherent and irreducible. It has nowbeen discovered that by imparting the described compound and continuousmotion to the piston, this source of noise is eliminated.

As heretofore noted, the inclination of the piston with respect to thehorizontal axis is also are required. Considering particularly Fig. '9,

Athe drive'sha-ft 28 is forrred on its periphery above the crank arm 63with a spiral groove 8|,

. utilized to provide a simple and effective lubricant pump, in which noadditional moving parts 84 .which communicates with the groove 8|through a radial port 85. 'The crank pin 62 is formed with a radial slot86 which intersects the duct 84, and the lower' end of the duct, belowthe slot 86, isv stopped oi with a plug 81 after the shaft has beenmachined. 'The crosshead 66 is formed with a transverse or verticalgroove 88, which maybe machined in the wall ofthe bore 65 from one endthereof al sufficient distance to overlap the radial slot 86 when theparts are assemble'd, YThe crosshead. .66 is also formed with anangularly inclined, transversely disposed or tangential slot"89,-disposed on the external surface and extending upwardly from the bottomof the bore 65, and in spaced relation to the groove 88. `An oil groove90 is also formed circumferentially of the crosshead 66, to supplylubricant to the bearing surface against the yoke 61.

Ihe .yoke 61 is formed with a port 9|, positioned above the lower traceof the yoke, and which is. in open communication with a flattenedsuction orriser tub'e 92, welded to the bottom of the yoke, the lowerend of which is adapted `to dipinto the oil bath. Both the tangentialslot 89 and theoil groove 90 are adapted to pass over the port 9| whenthe compressor is operated.

It will now be apparent that, as the piston 6| reciprocates, its yokeend moves downwardly with respect to the crank pin 62 on the suctionstroke, and'upwardly on the compression stroke, due to the inclinationof the piston with respect to the horizontal. Inasmuch as the lower endofthe crankpin 62 `is adjacent the junction of the bore 65 with the wallof the crosshead 66, there is a small well or reservoir 93 constituting,in effect, a cylinder or pump chamber in which the crank pinreciprocates as a piston. Referring again to Figs. `3 -to` 8, it will beseen that, as the piston 6| reaches the end of its compression strokeFig. 5-) the angularslot 89 in the crosshead 66 is about to registerwith the port 9| in the yoke 61, and thus place the slot 89 in fluidcommunication with the oil bath. As the shaft 28 continues 'to rotate,this communication becomes fully established, as shown in Fig. 6, andthe reservoir 93 also is in fluid communication with Vthe oil bath,since the slot 89 extends downwardly thereto, as is clearly shown inFig. 8. The crosshead is moving downwardly over the crank pin 62, toincrease the volume of the reservoir 93, and the suction effect causesoil to flow into the reservoii` as long as the fluid passageway is open.

During this same time, the trailing edge of the radial slot 86 in thecrank pin 62 has moved past the longitudinal duct 88 in the crosshead,thus closing off this passage, and preventing flow of oil therethrough.-As the crosshead 66 moves back to its central position the port 9|progressively closes, and is cut oi by the body of the crosshead as theend of the suction stroke is reached, as shown in Fig. 3. As thecompression stroke begins, the leading edge of therradial slot 86 opensthe duct 88, and the pressure Icreated by the upward motion of thecrosshead 68' with respect to the crank pin 62 forces the oil into theradial slot 86, and thence into' the longitudinal duct 84. The lubricantis then distributed asheretofore described.

It has heretofore been stated that the actual' inclination of the pistonto the horizontal, and the crank pin to the vertical, may be a smallangle of only two or three degrees. Preferably, both piston and crankpin are inclined, and they are inclined equally with respect to theirreference axes.

invention. For example, further consideration of the Figures will showthat, with equal angularities, the axes of the crank pin and the pistonare However, this condition need not be fulfilled within the broaderprinciples of the at right angles to each other when the crank pin 4 hasrevolved 180 from the position shown in` be vertical. references tovertical and horizontal planes and axes are made for convenience ofdescription, and not to -limit the invention to compressors mounted inone specific manner.

It will thus be seen that a positive displace-I ment oil pump has beenformed from the basic elements of the driving connection itself, thatis. .the drive shaft, crosshead, and yoke, and in which no additionalmoving parts are required. In my prior application, a system of portingthrough the driving elements is also disclosed, but

with added parts to provide a pump cylinder and.

piston. As with the lubricant pump of myprior invention, the presentpump is so organized as to have its suction and pressure strokescoincide substantially with the suction and compression strokes of therefrigerant compressor.

The present pump is quite noiseless in operation, and, while thedisplacements are numerically small, they are sucient to supply adequatequantities of oil to the bearings and other working parts. In fact, thepresent pump delivers enough oil that a portion of it may be sprayedagainst the casing walls to aid in cooling, being thrown offcentrifugally from the exposed upper end of the groove 8|, while theremaining portion drips through the rotor gap to lubricate the piston.The provision of the depending suction or riser tube 92 on the yoke 61makes it unnecessary to submerge the yoke and cylinder block in thelubricant.

While the invention has been described with respect to a singleembodiment thereof, it will be apparent to those skilled in the art thatnumerous modifications and alterations may be made without departurefrom its principles. It is therefore intended that the invention shouldbe accorded a scope commensurate with that expressed inthe followingclaims.

I claim:

n 1. A compressor having a crankcase portion and a cylinder block formedwith a cylinder bore, a piston reciprocably mounted in the cylinder boreand provided with a transversely disposed yoke at the crankcase endthereof, a crosshead slidably mounted in the yoke and formed with Inthis case.

When a larger, inclination of the piston is desired, and noise is. notso much of a factor, the crank pin axis mayl` It will, of course, beunderstood that4 a diametrical bore, a drive shaft having a crank pinportion rotatably mounted in the crosshead bore. a bearing for rotatablymounting the drive shaft for rotation about its own axis, said cylinderbore and piston being angularly inclined with respect to the axis of thedrive shaft,.said yoke being positioned with its axisl at right anglesto the axis of the piston, whereby upon rotation of the drive shaft thecrank pin and crosshead bore have linear movement relative to eachother. an oil duct extending longitudinally of the crank pin to thedrive shaft bearing, an oil bath in the crank case portion, and portsformed in the crosshead adapted to be alternately opened and closed intimed relation to the linear movement of lthe crosshead to alternatelysubject oil in the oil duct to pressure and to replenish oil dischargedfrom the duct fr om the oil bath.

2. A compressor having a reciprocable piston mounted in a fixedcylinder, said compressor having a crank case portion adapted to containa bath ofl oil, a. drive shaft formed with a crank pin inclined to theaxis of the drive shaft, a bearing for supporting the drive shaft forrotation about its own axis, a crosshead having a'diametrical bore inwhich the crank pin is rotatably mounted, a yoke surrounding thecrosshead and connected to the piston with the axes of the piston andyoke at right angles to each other, said yoke having an imperforate wallbeneath the bore of the crank pin, said piston having its axis inclinedto the axis of the drive shaft, whereby upon rotation of the drive shaftthe piston will reciprocate linearly in the cylinder and will alsooscillate about its own axis and said crosshead will reciprocatelinearly in the yoke, oscillate about its own axis, and reciprocatelinearly of the crank pin to change the volume of the space between theend lof the crank pin and said imperforate wall of the yoke, portingmeans formed in the crosshead and adapted, when said space is increasingin volume, to place said space in communication with the oil bath, anoil duct extending longitudinally of the crank pin to said bearing, andadditional porting means between the pin and duct to place said duct incommunication with said space when it, is decreasing in volume.

3. In a compressor having a supporting casting and a drive shaftrotatably mounted in a bearing in the cast-ing for rotation about itsown axis, a cylinder block formed with a cylinder bore connected to thecasting, a reciprocable piston in the cylinder bore, said piston andbore having a common axis inclined to the axis/ of the drive shaft, ayoke connected to the crank case end of the piston, the axis of the yokebeing disposed at right angles to the axis of the piston andtransversely of the shaft axis, a cross head formed with a diametricalbore slidably mounted in the yoke, a crank pin on the drive shaftrotatably mounted in the crosshead bore, the end of the crank pinterminating short of the end of the bore to form a reservoir between theend of said crank pin, the wall of the bore, and the wall of the yoke, alubricant duct having one end adapted to be placed in commiuiicationwith the reservoir extending longitudinally of the crank pin to thedrive shaft bearing, valve means in the crank pin and crosshead forestablishing said communication during one phase of rotation and forinterrupting'said communication during a successive phase, additionalvalve means in the crosshead and yoke for interrupting and establishingcommunication between said reservoir 9 and the exterior of the yokealternately to the operation of said rst named valve means, and meansexterior of lthe yoke to supply oil to said reservoir when saidreservoir is in communication with the exterior of the yoke through saidadditional valve means.

4. A combined refrigerant compressor and oil pump comprising a cylinderand a Apiston reciprocably mounted therein, a drive shaft and a bearingfor the drive shaft, and a, Scotch yoke connection between the shaft andpiston, said yoke comprising a yoke cylinder disposed at right angles tothe piston and connected thereto and a cylindrical crosshead slidablymounted in the yoke, a bore in the crosshead, a crank pin on the driveshaft rotatably mounted in the bore. said piston being inclined to theaxis of the shaft, a casing for the piston and shaft adapted to containa bath of oil, ports formed in the yoke and crosshead adapted to bealigned during one phase of movement of the shaft and piston and rocablepiston fitted in a fixed cylinder and a drive shaft rotatably mounted ina fixed bearing, a Scotch yoke connection between the shaft and pistoncomprising a cylindrical yoke connected to the crank end of the pistonat right angles to the axis thereof and a cylindrical crossheadreciprocably mounted in the yoke, said crosshead being formed with adiametrical bore and said drive shaft being formed with a crank pinrotatably mounted in said bore, the axis of the piston being inclined tothe axis of the drive shaft. saidY yoke being formed with an oiladmission port disposed within the outermost trace of the crossheadbore, said crosshead being formed with a tangential slot communicatingwith the bore and adapted upon reciprocation of the crosshead toperiodically register With and be displaced from said port, an oil ductformed in the crank pin and extending to the bearing, a radial slotformed in the crank pin communicating with the duct. and a groove in thebore adapted to register with the radial slot during that phase ofmotion of the crank pin and crosshead when the tangential slot isdisplaced from said port.

6. In a refrigerant compressor having av reciprocable piston fitted ina, fixed cylinder and a drive shaft rotatably mounted in a fixedbearing, a Scotch yoke connection between the piston and shaft includinga cylindrical yoke connected to the piston at right angles to the axisthereof, a cylindrical crosshead slidably mounted in the yoke and formedwith a diametrical bore, a crank pin on the drive shaft rotatablymounted in said bore, said piston being inclined to the axis of thedrive shaft and said crank pin also being inclined to the axis of thedrive shaft at an angle substantially equal to the inclination of thepiston to said shaft, an oil reservoir formed between the end of thecrank pin. crosshead bore, and yoke surface, a crank case for thecompressor containing a bath of oil, and porting means formed in thecrank pin, crosshead, and yoke adapted upon successive phases ofrotative movement of the shaft to admit oil from the crank case to thereservoir and to transfer oil from the reservoir to the bearing.

7. A hermetic refrigerant compressor comprising a casing having asupporting casting therein, a motor mounted on the casting, a bearingformed in the casting and a drive shaft rotatably mounted in thebearing, said drive shaft projecting beyond the bearing at each endthereof and being formed with an oil groove, a cylinder block mounted onthe casting and formed with a, cylinder bore, a piston reciprocablymounted in the cylinder bore, a cylindrical yoke connected to the crankend of the piston at right angles thereto, said piston and cylinder borebeing inclined to the axis of the drive shaft, a crosshead slidablymounted in the yoke and formed with a diametrical bore, a crank pinformed on one end of the drive shaft and extending beyond the bearingand rotatably mounted in the crosshead bore, a. bath of oil in thecasing, an oil duct formed in the crank pin and communicating with theoil groove of the drive shaft, ports formed in the yoke and crossheadadapted to register during one phase of movement of the drive shaft toadmit oil from the oil bath to the region between the end of the crankpin, crosshead bore, and yoke, other ports formed in the crank pin andcrosshead adapted to place said region in communication with said oilduct during a successive phase of movement, said oil groove extendingthe full length of the drive shaft and to the opposite end thereofbeyond said bearing, whereby oil forced into said groove may betransferred from said opposite end of the shaft to the motor and thecasing walls to absorb heat therefrom, and a drain duct in said castingadjacent the crank end of the piston and cylinder block to direct atleast a portion of the oil to the piston.

JENS TOUBORG.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,744,791 Nemetz Jan. 28, 19301,814,285 Butler July 14, 1931 2,153,773 Patrignani Apr. 11. 1939'2,239,723 Limpert et al. Apr. 29, 1941

